The present invention relates to a pneumatic tire for motorcycle, more particularly to a tread pattern for street use capable of improving transient characteristic and ride comfort while securing wet performance.
A motorcycle tire is required to have stable handling characteristic on dry roads from the upstanding state during straight running to a leaning state during cornering and vice versa. Especially required are appropriate suppleness (ride comfort) and transient characteristic which is uniform even if the leaning angle of the tire is changed. On wet roads, on the other hand, a high aquaplaning resistance is required. It is effectual for improving the aquaplaning resistance to provide grooves whose inclination angle is small with respect to the tire circumferential direction. However, such grooves have a tendency to decrease the generation of lateral force (such as cornering force and camber thrust) necessary for providing a good cornering performance on dry roads.
Japanese Patent Application Publication No. 06-55909 discloses a motorcycle tire, wherein in order to improve wet performance and cornering performance, a circumferentially continuously extending groove is disposed on the tire equator, and oblique grooves whose angle with respect to the tire circumferential direction is gradually increased toward the axially outside of the tire are disposed on each side of the tire equator.
In such a tread pattern, however, it is difficult to uniform the transient characteristic from the upstanding state during straight running to a leaning state during cornering and vice versa, therefore, there is still room for improvement in the cornering performance.